Effect of temperature on the formation of dynamic magnetic domains in ferrite-garnet films

Dynamic domain structures in ferrite-garnet films (111) with normal anisotropy are investigated for the temperature range of 77–300 K. The boundaries of the area of the existence of one- and two-armed spiral domains are determined as a function of the temperature, frequency, and amplitude of the vertical field. It is found that the region of the existence of spiral dynamic domains shift toward low frequencies when the temperature is reduced.     

Magnetooptical effects in bismuth-containing ferrite-garnet films

We present results of magnetooptical investigations of bismuth-containing ferrite-garnet films with the easy axis of magnetization parallel to the specimen surface. Measurements were conducted for incident light with energies in the range 1.5–3.2 eV for transverse [equatorial Kerr effect (EKE)] and for longitudinal [meridional intensity effect (MIE)] magnetizations of thin-layer specimens. It is shown that the EKE differs from zero when the films are opaque, and it is established that the EKE peak in the region 2.8 eV increases with increasing bismuth concentration. For longitudinal magnetization, conditions for observing magnetooptical interference were realized. The experimental curves agree well with the theoretical ones.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 10–14, November, 1989.     

A mixed domain structure in ferrite-garnet films

A stable static mixed domain structure consisting of strip domains and a cylindrical magnetic domain (CMD) is obtained in (Bi_0.7Lu_0.3)₃ (Fe_0.8Ga_0.2)₅ O₁₂ ferrite-garnet films. An analytic theory of the mixed domain structure is constructed. An analytic solution is obtained for the shape of a distorted strip domain, which is in good agreement with experimental results.     

Anomalies of magnetooptical diffraction in ferrite-garnet films

Experimental magnetooptical diffraction spectra produced by the band domain sructure in an epitaxial ferrite-garnet film are described. Asymmetry of the optical field in symmetric maxima is observed when a laser beam is normally incident on the sample. Analysis of the experimental data shows that the factors responsible for disrupting the symmetry of the magnetooptical diffraction spectrum include the inclination of the domain walls and inequality of the Fresnel coefficients fors andp polarizations of the incident radiation. Ul'yanovsk State Unviersyt. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 68–71, September, 1997.     

Bias-field-induced spiral dynamic domains induced in iron garnet films

The induction of an Anger state (AS) in a multidomain magnetic medium by a static bias magnetic field is observed. The properties of the spiral dynamic domains in the induced AS are substantially different from those of previously studied spiral domains. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 1, 60–64 (10 January 1997)     

Dynamic drift of the magnetic domains in ferrite-garnet crystals

The drift of stripe-domain walls in a (111) ferrite-garnet plate with orthorhombic anisotropy and quality factor Q < 1 in an alternating magnetic field of 30–1000 Hz was investigated. The obtained experimental dependences of the domain wall drift velocity on the magnetic field frequency and amplitude are compared to the corresponding theoretical dependences.     

Surface fastening of domain boundaries in epitaxial ferrite-garnet films

The process of quasistatic shifting of domain boundaries (DB) in weak magnetic fields is studied in epitaxial ferrite-garnet films (EFGF). The investigations were performed by using the Faraday magnetooptical effect by the method of domain boundary oscillation in a variable magnetic field and by recording small shifts in a permanent field. Artificial fastening of EFGF DB is performed on the film surface-air by fields of scattering from a thin MnBi layer deposited on the EFGF with a different magnetization state. The assumption of DB fastening in EFGF on the film-substrate transition layer is confirmed experimentally. The influence of the transition layer characteristics on the magnitude of the EFGF coercive force is discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, No. 11, pp. 52–57, November, 1989.The author is deeply grateful to A. G. Shishkov for discussing the research.     

Microinhomogeneities in the distribution of oxygen concentration in ferrite-garnet films

Artificial microinhomogeneities were created in iron-garnet (TmBiCa)₃(FeGa)₅O_12−γ films with various degrees of oxygen nonstoichiometry, changes in the individual magnetic characteristics of these inhomogeneities were tracked during chemical oxidation and reduction, and the interactions of these inhomogeneities with planar domain walls and spiral domains were investigated. The resulting experimental data were interpreted by analyzing how the saturation magnetization, domain-wall surface-energy density, and uniaxial anisotropy constants depended on the concentrations of different-valency iron ions, cationic vacancies, and anionic vacancies. Fiz. Tverd. Tela (St. Petersburg) 41, 2016–2019 (November 1999)     

Mechanism of drift of stripe magnetic domains in ferrite-garnet single crystals

The drift of stripe magnetic domains in (111) single-crystal ferrite-garnet plates in an alternating magnetic field (25–1000 Hz) has been investigated. The dependences of the drift velocity of stripe domains on the field frequency and amplitude have been obtained for magnetic fields of different orientations. A dislocation drift mechanism is proposed. Enhanced motion of magnetic dislocations in a system of stripe domains is established.     

Nonlinear dynamic magnetization regimes in (100) ferrite-garnet films

To study the nonlinear dynamics of a uniformly precessing magnetization in perpendicularly magnetized (100) ferrite-garnet films, equations of motion are numerically solved over a wide ac field frequency range. Bifurcation changes in the magnetization precession and the states of dynamic bistability have been detected. The conditions of high-amplitude regular and stochastic dynamic regimes are revealed, and the possibilities of controlling these precession regimes by applied magnetic fields are shown.     

Evolution of spiral dynamic magnetic domains in Anger states of iron garnet films

Dynamic domain structures in the Anger state of iron garnet films are analyzed by a video micrographic technique. Data are obtained on the evolution of individual spiral domains over the lifetime of each domain. A new mechanism for the destruction of this state is discovered. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 6, 453–456 (25 March 1996)     

Finite lifetime of spiral domains in the anger state of multidomain magnetic films

The finite lifetime T _g of a dynamic spiral domain in the anger state in a multidomain film with perpendicular magnetic anisotropy is estimated theoretically in the framework of a dissipative model. The finite lifetime of spiral domains is investigated as a function of the frequency of an external ac magnetic field that varies according to a harmonic law.     

Unidirectional anisotropy of the velocity of domain walls in ferrite-garnet films

A mechanism to explain the gigantic unidirectional anisotropy of the velocity of domain walls, which includes the local rotation of the magnetization in front of a moving domain wall, initiated by radiated spin waves is proposed. Institute of General Physics, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 45–48, September, 1997.     

Dynamics of domain walls in orthoferrites in the light of results obtained for ferrite-garnet films

Results obtained for monocrystalline films of ferrite-garnets (FGMFs) are used to explain why the generation of microdomains ahead of a moving domain wall (DW) has been observed for orthoferrites in experiments involving the dynamic growth of multiple domains but has not been seen in experiments in which the motion of an isolated DW was studied. The explanation is based on the dependence of the dimensionless decay parameter on the constant magnetic field applied in the plane of the film (plate). Institute of General Physics of the Russian Academy of Sciences, at Mordovia State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. 1, pp. 59–63, January, 1999.     

Study of the fast dynamics of domain walls in ferrite-garnet films in the presence of large in-plane fields

The dynamics of domain walls in ferrite-garnet films with orientation (111) was investigated by twofold digital high-speed photography. The experiments were performed in the presence of an in-plane magnetic field comparable to the anisotropy field of the samples.     

Stable patterns of membrane domains at corrugated substrates

Multicomponent membranes such as ternary mixtures of lipids and cholesterol can exhibit coexistence regions between two liquid phases. When such membranes adhere to a corrugated substrate, the phase separation process strongly depends on the interplay between substrate topography, bending rigidities, and line tension of the membrane domains as we show theoretically via energy minimization and Monte Carlo simulations. For sufficiently large bending rigidity contrast between the two membrane phases, the corrugated substrate truncates the phase separation process and leads to a stable pattern of membrane domains. Our theory is consistent with recent experimental observations and provides a possible control mechanism for domain patterns in biological membranes.